Year Letter Designations for Beef Cattle Numbering - CattleTags.com
International letters are designated for each year of birth. This option is easy to use in conjunction with numbers. For example, Z001 and Z002 might be used to indicate the first and second calf born in the year 2012.
Note: The letters I, O, Q, and V are not used.
Source: Beef Improvement Federation
An example of an effective numbering system
As an example: 100M has a heifer calf in 2013 tagged 100A (100 from the dam, A from the year letter). If that heifer is sold then she keeps the tag. If she is kept as a replacement heifer, she would receive the next new number available (say 205) and thus be retagged to 205A. This ensures we don't end up with two calves with the same tag number.
If you have an existing herd that will not be retagged, you can begin adopting this system going forward with future purchases and replacement heifers. If you have cows that you are uncertain of age, you can either leave the letter part off or use the oldest possible letter.
The system above is one that we recommend and tags can easily be printed with your numbering system so you don't have to deal with messy markers or power tools.
How to have year letters printed on your cattle tags
While many feed supply stores have pre-numbered tags, they do not include year letters. Producers must instead use a marking pen to mark the year letter and tag number on a blank tag. Unfortunately the ink can fade over time leaving just a blank tag.
A better way for around the same price is to order custom cattle ear tags where you can specify your own management codes including letters and numbers. We are always glad to help, so feel free to contact us if you need assistance.